The thing is that for Russia to "win" it must at least win against Ukraine before going at its strategic adversary (US/NATO).In the meantime, as long as battles soften up the AFU over time, it is advantageous to Russia but will not create the conditions for victory unless Ukraine does a huge blunder.
For NATO to win, it only needs to bleed Russia dry at this Ukraine-Russia war.
Do you see now why for Russia, even winning against Ukraine doesnt mean much because NATO is pretty much untouched while Russia itself will suffer from being directly engaged in a war (economically, technologically, industrially).
That's why Russia needed to stearmroll Ukraine in the first months so that it could minimise this war-damage. Russia biggest opponent isn't Ukraine, its NATO